[FFmpeg-user] Best way for converting HD 1080i to DVCPRO25 DV?

[Andy Furniss]

Iban Garcia wrote:
> Hi Andy,
>
> First of all, thank you for your interest and help.

Hi, I re-added list cc as I don't really know what I am talking about :-)

> Why DVCPRO?
> The reason for getting an DVCPRO50 interlaced is because I need to play it
> in a Mediaport (OMNEON) -->
> http://www.omneon.com/downloads/specsheets/Spec_DV_MPEG_IMX_MediaPort.pdf

OK.

> I am looking for the best way to transcode 1080i (DVCPRO-Intra) to DVCPRO50
> (interlaced).
> I think that there are two keys to achieve the best resoults in transcoding:
>   - Image scaling (http://en.wikipedia.org/wiki/Image_scaling)
>   - Unsharping after down-scaling

I see googling around, that final unsharp and prefiltering high 
frequency before the scale is the way people downsize photos.

I think there will be a problem if you unsharp a weaved frame, so I 
guess you'll need to try and work with fields if that's possible.

You should also keep in mind what I said about sharp interlace - you 
don't really want to have fine detail that only appears in one field or 
you run the risk of getting twitter.

I am not familiar enough with ffmpeg to give direct examples, or even 
know all that's available. Maybe someone else knows how to soften before 
scaling.

>
> DVCPRO is bff, but... fieldorder=tff is a way to get after transcoding, a
> dvcpro with the correct fieldorder. I remember that if I set up
> "fieldorder=bff" the fields played in a bad way.
>
> For now, I am looking for the best command to get it, something like this,
> but with good parameters ;-):
> #-----------------------------**------------------------------**
> -----------------------
>      $comand="ffmpeg -y -threads 8 -i ".$input_file.".mxf -pix_fmt
> yuv422p -aspect 16:9 -vf \"scale=720:576:interl=1,**fieldorder=tff\"
> -sws_flags lanczos -vcodec dvvideo -an ".$output_file.".dv";
> #-----------------------------**------------------------------**----------------------

For some reason I see the opposite to you - I have a tff source and if I 
encode with fieldorder=tff I get a dv that ffplay or mplayer assumes is 
bff - so any field rate deinterlace will judder unless I override 
(mplayer) with field-dominance 0.

However if I encode it with fieldorder=bff then it really does seem to 
produce bff weave, so things work by default and specifying 
field-dominance 0 produces the wrong output.